THE SUNTHE

BEGINNING

THROUGH

THE ENDBy: James Wadley

Outline – Stages of Sun’s Existence

1. Molecular Cloud

2. Proto-Sun

3. Hydrogen Fusion

4. Main Sequence

5. Subgiant

6. Red Giant

7. Helium Burning Sun

8. Double Shell Burning Red Giant

9. Planetary Nebula

10. White Dwarf

11. Black Dwarf

1. Molecular Cloud• Collapsed as gas was pulled to dense regions by

gravity

• Cloud fragmented into smaller pieces

• Contracting gas quickly radiated most of the

energy

• Not enough heat and pressure for gravity

resistance

2. Proto-Sun• Dense center trapped infrared

radiation

• Heat and pressure increased

dramatically

• Gravity and pressure caused

contraction

• Birth of our Proto-Sun

• Surrounding gas continued to add mass

• The more contraction the faster the

rotation

• Cloud flattened into a disk because of

collisions

• Angular momentum kept the disk

spinning.0

3. Hydrogen Fusion• At first the fusion process was unstable

• Stable hydrogen fusion was reached at around

10 million Kelvin

4. Main Sequence • The Sun is an estimated 4.55 billion years old

• The main sequence stage is around 10 billion

years

• Slight increase then decrease in temperature

• Slow evolution during consumption of its

hydrogen core

• Little increase in growth and luminosity

5. Subgiant • The Suns subgiant stage will begin around the

age of 11.6 billion years

• This will be a rapid growth cycle for about 600

million years

• Strong stellar winds result in the estimated loss

of %28 of its mass

6. Red Giant • Core hydrogen is exhausted

• Core shrinks and heats

• Hydrogen shell burning begins around the inert

helium core

• Expands into a red giant

7. Helium Burning Sun• Core heats enough to fuse helium into carbon,

starting helium fusion

• Core expands

• Slows rate of hydrogen shell burning

• Sun’s outer layers will then shrink

8. Double Shell Burning Red Giant

• Core helium is exhausted

• Helium shell burning begins around the inert

carbon core

• Fusion in both hydrogen shell and helium shell

• Enters second red giant phase

9. Planetary Nebula• Expels its outer layers in a planetary nebula

• Exposed inert core is left behind

10. White Dwarf• Made primarily of carbon and oxygen

• The low mass Sun won’t grow hot enough to

produce heaver elements

11. Black Dwarf• A white dwarf that has cooled down

• It is the temperature of the cosmic microwave

background

• Black dwarfs are hypothetical unlike red, brown

and white dwarfs

Conclusion•As with humans, the Sun has been and always will

be our Sun.

•The Sun will go through many stages and show

many faces.

•A man’s prime 20-30, the Sun’s is during the main

sequence.

References

1. The Essential Cosmic Perspective – Fifth edition

– Jeffrey Bennett, Megan Donahue, Nicholas

Schneider and Mark Voit

2. http://www.astronomy.ohio-state.edu/~pogge/L

ectures/vistas97.html

3. http://www.universetoday.com/41096/black-dwa

rf/